Plant Biology and Biodiversity Management

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Browsing Plant Biology and Biodiversity Management by Author "Abate Dawit (PhD)"

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    Antifungal Metabolites from Submerged Culture of Ganoderna Lucidum (Polypore)
    (Addis Ababa University, 1991-06) Bitew Adane; Abate Dawit (PhD)
    About 60 different basidiomycete cultures were screened for antimicrobial secondary metabolites in submerged culture grown in four different media. Ten (17%) of them produced antimicrobial secondary metabolites. Production medium, duration of growth, and the most susceptible test organisms for each producing strain were established. Among basidiomycetes screened for antimicrobial activity, the culture filtrate extract of the Ethiopian strain of the polypore, Ganodemw lucidum produced the most effective antifungal compounds. The cu/~lral characteristics, growth in submerged culture of the polypore and isolation methods of the two antifungal antibiotics are described. Medium A (Yeast extract malt extract glucose medium) was a better medium for the production of the two antifungal agents. These compounds were released to the culture fluid and the maximum amount of antifungal compounds is obtained after 12 days of submerged growth at 120 revolution per minute (rpm). TIle two antifungal metabolites (20lA and 201B) isolated from culture filtrated were biologically characterized. TIlese metabolites had a wide spectrum of antifungal activity and affect the growth of several saprophytic as well as pathogenic fungi. The minimal inhibitory concentration (MIG) of 20lA against Candida albicans and Candida pseudotropicalis was less than 1 mcg/ml and 1-5 mcg/ml respectively. Inhibition diameter zone of 36 mm was produced when 10 mcg/disc of 20lA was applied on agar medium seeded with AspergHlus flavus. 20lA was also a potent inhibitor of spore gemlination. No spores of Aspergillus niger were germinated at a concentration of 10 mcg/ml of the antibiotic. Bacteria were affected only at high concentration. Antibiotic 20lA was more active than antibiotic 201B. A comparison of antifungal activity against dennatophytes showed that the efficacy of 20lA was comparable to griseofulvin. Treatment of sheep erythrocytes with the two antifungal antibiotics up to 100 mcg/disc did not show any lytic effect on sheep red blood cel/s. Application of 1 mg/1Ocm' of cn/de extract on a shaved rabbit skin showed no demlatotoxic reactions.